Propulsion systems for gas turbine engines, such as those that power modern commercial aircraft, typically include noise suppressing structural panels. These structural panels are typically comprised of a plurality of cellular structures or cells between two skins. These cells are often arranged in a lattice, such as a lattice resembling a plurality of “honeycomb” shaped cells. These noise suppressing structures may be utilized in engine components such as nacelles.
Nacelle designs are trending towards larger fan diameters and thinner architectures, reducing the room for effective acoustic treatment. The lower rotational speeds of larger fan diameters are associated with lower frequency and the increased size of the blades could potentially generate significant tonal noise levels, and typically, thicker panels would be needed to target these frequencies. However, increased thickness means heavier acoustic panels, and more importantly, an increased thickness of an acoustic panel means the overall diameter of the nacelle increases, increasing the size and weight of the entire structure.